Osteoarthritis is a common degenerative joint disease that affects millions of people worldwide, particularly among the aging population. The symptoms of osteoarthritis include cartilage damage, subchondral bone sclerosis, osteophyte formation and synovial membrane inflammation. These symptoms worsen over time, causing pain and disability at the affected joints. Therefore, osteoarthritis significantly affects a patient's quality of life. The pathogenesis of osteoarthritis is complex and not fully understood. It is recognized that mechanical stress on the joint can lead to cartilage degeneration over time (wear and tear). Genetic factors contribute to osteoarthritis pathogenesis as the intrinsic quality of the cartilage and the anatomy of the joint can develop in ways that are more prone to damage. Inflammation is also involved in osteoarthritis development. Pro-inflammatory cytokines such as interleukin-113 (IL-1ß) and tumor necrosis factor-α (TNF-α) are elevated in osteoarthritis cartilage, synovial fluid, synovial membrane and subchondral bone. These cytokines suppress the synthesis of cartilage extra-cellular matrix (ECM) and increase the production of matrix metalloproteinases (MMPs) which degrade type II collagen in the cartilage. Inflammation of the synovial membrane, or synovitis, leads to the infiltration of inflammatory cells which secrete more pro-inflammatory cytokines, aggravating the diseased condition by further increasing MMP production. Currently there is no cure for osteoarthritis. Existing treatments aim to alleviate pain and improve joint function through non-pharmacological and/or pharmacological modalities. If a patient does not benefit from a combination of non-pharmalogical and pharmalogical treatment, joint replacement surgery can be considered.
In recent years, flavonoids have attracted much attention because they have been recognized to have biological and pharmacological properties. However, the activity half-life of flavonoids is limited to a few hours inside the body. Therefore, despite the favorable properties of flavonoids, it is impractical to achieve a therapeutic level of this compound in the body by directly ingesting a large amount due to inherent volume constraint. That is, in order to obtain a therapeutic or pharmacological benefit from flavonoids through diet alone, it would be necessary to ingest an amount of food and beverage that is larger than is practical to consume.
In cases of flavonoids consumed via oral intake of foods and beverages, the flavonoids may play a role as antioxidants to protect the digestive tract from oxidative damage during digestion. However, flavonoids can be expected to remain only in the digestive tract and thus their beneficial physiological activities are not likely to be utilized in tissues. Moreover, their strong hydrophobicity as well as their tendency to form complexes with proteins makes parenteral delivery of these compounds difficult.
There is therefore a need to provide a treatment that overcomes, or at least ameliorates, one or more of the conditions described above.